Heretofore, characteristics of an optical device such as an LED or an LD have been controlled or improved by forming a periodic structure of a light wavelength degree on the surface of the optical device or in the device. The periodic structure for such a purpose is formed by various types of fine processing, and one of such technologies considered to be most dominant at present is a nanoimprint technology. A mold (the die) for use in nanoimprint die transfer is usually prepared by an optical exposure device.
Here, as the mold for use in the die transfer, there are developed a flat plate-like mold for use in flat plate pressing, and additionally a roller-like mold (the roller mold) which enables continuous transfer to a film while rotating. Heretofore, the roller mold has been prepared by attaching a flexible material such as a metal thin film to a roller, but in this case, there is a cut in the mold to which the material is attached. Therefore, when the roller rotates one revolution, a joint sometimes remains in the pattern. In this respect, according to a technique of exposing and depicting a pattern while rotating the roller mold, such a problem can be avoided.
Meanwhile, during the exposing while rotating the roller mold, heretofore, there has been performed a depiction technique (see FIG. 5) in which electron beams are focused on a lens and a resist is irradiated with the beams. Additionally, there is also suggested a simultaneous depiction technique (see FIG. 6) in which a stencil mask provided with an opening pattern is irradiated with electron beams formed into substantially parallel beams by a lens, and a resist is irradiated with the plurality of passed electron beams (see e.g., Patent Document 1). In the former case, when the electron beams are focused, an output at the focused position can be enhanced, which enables predetermined depiction on the resist at one irradiation time (one-rotation depiction). However, a region where the depiction is possible at a time is small, and hence a certain degree of time is required to depict the whole desirable pattern (throughput is small). On the other hand, in the latter case, a broad region is irradiated with the electron beams, and hence it is possible to increase the throughput. However, in the latter case, since the beams are not focused but are emitted, the output at each irradiation position is not high. In consequence, by multi-rotation depiction in which a groove-like pattern (see FIG. 7 and FIG. 8) is gradually deeply formed while rotating the roller mold many times, depiction performed through rotation at a low speed although the number of the rotation times is small (additionally, such a mold pattern is also called line and space owing to the configuration. See FIG. 7), or the like, it is necessary to lengthen a beam irradiation time of a depiction object area to a certain degree.